This invention relates to a process for the production of diphenylamine and its derivatives by dehydrogenation of wholly or partially hydrogenated diphenylamine and its derivatives in the presence of nickel/chromium catalysts.
Diphenylamine is of considerable industrial importance. It is known from German Published Pat. No. 2,331,878 to prepare diphenylamine and its derivatives by dehydrogenation of N-cyclohexylidene-aniline and its derivatives in the presence of a nickel catalyst on alumina or of a CuO--Cr.sub.2 O.sub.3 catalyst on SiO.sub.2. The catalysts however proved to have a low stability so that the yield of diphenylamine already drops down sharply after a few hours.